Hydraulic clutch



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' HYDRAULIC CLUTCH Nov. 16, 1948. A., F. HlcKMAN 2,453,981

mr'nmuuc simon Filed Nov. 15, 1944 2 Sheets-Sheet 2 NSQ Otlorlnegs Patented Nov. 16, 1948 HYDRAULIC CLUTCH Albert F. Hickman, Eden, N. Y.. minor u niekman Pneumatic Seat Co. Inc., Eden. N. Y., a `corporation of New York y Application November 15, 1944, serial Nn. 563,4ss

which will transmit heavy loads without danger y of breakage.

Another object is to provide such a clutch which can -be operated to provide any desired degree of slippage without appreciable wear upon the parts.

A further purpose is to provide such a clutch which can'be designed to provide a coupling in one direction, such as from the driving to the driven member, but is substantially completely open or uncoupled to reverse torque forces, that is, from the driven to the driving member.

Another object is to so arrange the pistons within the clutch so that a minimum of side thrust or other undesirable forces are imposed upon the pistons or other internal parts'of the clutch.

" chanical transmission through which the clutch operates.

Another object is to provide such a clutch which recirculates a part of its operating fluid through the adjacent casing for the mechanical transmission thereby to maintain proper lubri- A cation throughout; to utilize the mechanical transmission gear case as a large reservoir for lthe clutch; and to utilize the full externalarea of both the clutch and mechanical transmission casings to cool the liquid.

Another object is to provide such a clutch in which parts cannot become misplaced even if spring breakage should occur.

2 clutch embodying my invention, this section being taken on line I-I, Fig. 2.

Fig. 2 is a vertical transverse sectional view, taken on line 2-2, Fig. 1. I

Fig. 3 is an end elevational view.

Fig. 4 is an enlarged fragmentary sectional view, taken on line 4 4, Fig. 2.

The hydraulic clutch is shown as mounted on the casing 5 of a change speed transmission driven from a sprocket 6 which is fast to the tubular hub 8 of a gear i which hub is shown as journaled in one end of the casing 5 by a ball bearing i0. A shaft il is journaled in the tubular hub 8 of the gear 9, this shaft in being also journaled in a ball bearing i2 arranged in a bore I3 in the opposite end of the casing E. This -bore I3 is in communication with the interior of the casing 5 through the space between the races of the bail bearing i2 and leakage of ou from the bore is prevented by a welsh piug or sealing disk IB which is set into the bore i3. A nut I5 Aisprovided on the end of the shaft within the bore i8, this nut tightening against the inner race of the ball bearing i2 to hold the ball bearing and shaft axially in position in the bore i8.

The gear 9 is provided with spur 'teeth i8 meshing with the teeth oi a spur pinion i9, this pinion I9 being integral with a countershaft 20.

Other objects and advantages will appear from 1 the following description and drawings in which: Fig. 1 is a longitudinal sectional elevation through a transmission including a hydraulic This countershaft 20 is arranged parallel with the shaft ii and is shown as journaled at one end in a bearing bushing 2i mounted in a screw plug 22 in one end of the casing E and at its other end in a bearing bushing 23 in a bore 26 through the other end of the casing 5, this bore bei-ngI shown as sealed by a Welsh plug or sealing disk 25. l

The gear 9 is also provided with face jaws 28 adapted to engage the end jaws provided by the splineways 29 of a gear shift sleeve 30, these splineways 29 of the gear shift sleeve fitting splines 3l on the shaft ii so that the Sear shift sleeve 30 is compelled to rotate with the shaft il but can be moved axially along the shaft. This axial movement of the gear shift sleeve 30 is effected by a gear shift rod 32 which is slidably mounted in the gear case 5 for movement parallel with the shafts Ii and 20. One end of this gear shift rod 32 extends outwardly from the gear case 5 through a gland or stuffing box 33, so that it can be shifted manually, and with- Ain the gear case 5 this shifting rod carries a fork 3l which embraces the gear shift sleeve 30 and has its arms arranged in an annular peripheral groove 35 so that axial movement of the 3 shifting rod 32 is transmitted to the gear shift sleeve 38.

In one extreme position of the gear shift sleeve 30 its splineways 29 interengage withthe face jaws 28 of the gear 9 thereby to establish a direct drive between the drive sprocket 8 and the shaft I I. The gear shift sleeve 38 is also formed to provide spur gear teeth 38 which in the other extreme position of the gear shift. sleeve 80 mesh with a spur gear 39 integral with the countershaft 20. When so engaged, the drive from the sprocket 8 to the shaft I I is through the countersocket 18 for this purpose.

shaft 20 and hence the speed of rotation of the shaft II is decreased.

The gear case 8 is provided with a cover 40 for access to the gear case in assembling the gearing and with a capped stand pipe 4I through which the gear case is filled with oil.

The end 48 of the shaft Il winch projects from the hub 8 of the gear 8 is tapered and this tapered end is provided with an axial end bore 48 leading to a tapered valve seat 48, the small end of this tapered valve seat 48 leading to a small bore 48 which extends axially to the opposite end of the shaft II.

On this tapered end 48 of the shaft II is fixed, by means of a key 58 and a nut 8l. the cylinder block 52 of a hydraulic clutch. This cylinder block is provided at one end with a cylindrical hub 5I which is arranged adjacent the drive sprocket 8 and hub 8 of the gear 9 and on this hub 83 is rotatably mounted the hub 84 of a cylindrical shell 55. This cylindrical shell i5 has an end wall 58 extending radially outward from the hub 84 and a peripheral cylindrical wall I8.

It will particularly be noted that the inner cylindrical working face 58 of the cylindrical wall 88 is eccentric with reference to the axis of rotation of the shaft II.

To the rim of the cylindrical wall 58 of the cylindrical shell 85 is secured, by screws 88, or in any other suitable manner, a circular cover plate 6I, this cover plate having a closed hub 82 which is `journaled on the cylindrical hub 68 of the cylinder block 52 which projects toward the end of the shaft II. The screws 80 are also shown as securing a sprocket 84 to the cylindrical shell 8l, this sprocket preferably being concentric with the axis of the shaft Il. l

As best shown in Fig.` 2, the cylinder block 82 is square in cross section in a plane extending perpendicularly to the axis of the shaft II and from the corresponding end of each of the four faces 85 is provided with a bore 88 which extends along the adjacent face 85 of the cylinder block to provide a cylinder. The axes of these cylinders 68 likewise describe a square which is concentric with the axis of the shaft II but it will be noted that theI square formed by the four faces 88 ofthe cylinder block is offset, circumferentially', from the square described by the axes of the cylinders 88 so that the open end of each cylinder 88 slopes toward its adjacent wall 88. By this means ,each of the cylinders 88 is longer on that side which receives the side thrust from the pistons, as hereinafter described.

In each of the cylinders 88 is fitted a piston or 'spherical end 10 thereof. A smaller axial bore 12 extends inwardly from the spherical end 18 of each piston to the large bore 1I thereof. A

helical compression spring 14 is arranged in each piston. one end being seated against the outer extremity of the piston and the other end being seated at the bottom of the cylinder 88. These springs 14 therefore urge the pistons 88 axially outward. v

On the spherical end 10 of each piston is mounted a shoe 18, each shoe having a spherical Each shoe is provided with a curved outer face 18 which conforms to the cylindrical working face 88 of the cylindrical shell 58 and with parallel sideflanges 'I8 which ride along the side walls I8 and 4I of the cylindrical shell so as to hold the shoes in alinement. At its leading edge each shoe 18 is preferably formed to provide a wedge-shaped crevice 80, this crevice serving to provide a molecular congestion of the oil between each shoe 1l and the working face 58 and insuring proper lubrication therebetween.

Each shoe 15 is provided with a central port II which communicates 'with the bore 12 of the corresponding piston 88 and is open at the working face 18 of the shoe. As the cylinder 8l rotates relative to the cylinder block 82, these ports 8l pass into and out of communication with a semicircular groove 84 provided in the working face U8 of the cylindrical shell 58. The one end of this semicircular groove 84 terminates approximately in a plane intersecting the axis of the shaft Ii and the most salient portion of the cylindrical shell 55, and with the arrangements of parts as shown, this groove extends around the upper half of the cylindrical shell 58 as viewed in Fig. 2.

From the bottom of each cylinder 88 a bore 88 extends vlaterally to the tapered face of the shaft I I and this tapered portion of the shaft .II is provided with ports 88 which register, respectively, with these bores 88 and open into the tapered or conical valve seat 48 between the bores 46 and 48 of the shaft II. The flow of oil from these ports 88 is controlled by a valve stem 88 having a tapering end moving toward and from the seat 48. For this purpose the valve stem 88 is arranged coaxially in the larger bore 48 of the shaft I I and extends out through a stuffing box or gland 88 in the end wall of the hub 82 of the cover plate 8i for the cylinder 85.- The axial adjustment of the valve stem 88 can be controlled from the exterior of the clutch in any suitable manner. A bore 8l is provided through the shaft II and cylinder block 82 and leads from the bore 48 in the shaft il to the chamber enclosed ,by the cylinder Il.

To prevent the pistons from possibly hanging up on'encountering reverse torque, that is, reverse force from the driven sprocket 84 to the driving sprocket 8,'as when going down hill or vfor any other reason, means are provided for insuring that the pressure of the springs 14 is always adequate to urge the pistons outwardly into engagement with the shoes 15 and the shoes 'into engagement with the working face I8 of the cylindrical shell 85. Otherwise the pistons might remain retracted on encountering the eccentric part of the cylindrical shell and free the shoes 18 or at least cause an undesirable noise. The `means for this purpose comprise a check valve 88 for each cylinder 88 which insures that the pressure of the oil in the chamber enclosed by the cylindrical shell 88 never substantially exceedsthe pressure within the several cylinders Il.

For this purpose -each shoe is provided with a bore 84 which extends parallel with the shaft II and one end of which is formed to provide a.

reduced annular shoulder' 88 against which a A filling plug |55 can be provided inthe cylinder 55 and suitable oil seals i5| and.l |52 can be provided at the hub of the sprocket 5. Further, to positively insure against any piston 55 losing its shoe 15. as, for example, if its spring should break and wind up, the flanges 19 on opposite sides of these shoes preferably are curved to conform to the working i'ace |59 of the cylindrical shell and ride in tracks or grooves |58 provided in the side wail 55 of the cylindrical shell 55 and its cover 5I, respectively. It will -be seen that any shoe which becomes wholly freed from its piston 551sr merely pushed around the tracks |05 and does not interfere with the working of the other parts of the clutch. s

In the operation of the transmission, it is assumed that the cylindrical shell 55 of the clutch and the ltransmission casing 5 is nlled with oil,

this being supplied through the lling opening 5| and plug |80. Power from the drive sprocket 5 is transmitted to the shaft either directly, through the :laws 25, or indirectly, through the countershaft 25, depending upon the position of l the gear shift sleeve 85 as determined by the gear shift -rod 52 and its yoke 84.`

As the shaft il rotates, it rotates the cylinder block 52 keyed thereto. thisggmovin'g the pistons 55 and their shoes 15 totravel around the cylindrical; shell 55, the outer faces of these shoes traversing the working face 59 of this cylindrical shell. The cylindrical shell 55 is journaled on the eccentric hubs 53 and 53 of the cylinder block 52 and hence the rotation of this cylindrical shell is eccentric to the axis of the cylinder block 52. Consequently as the cylinder block rotates relative to the enclosing cylindrical shell 55, the pistons 58 are reciprocated in and out, the inward movementrbeing eected by the inwardly offset part of the working face 59 and the outward movement of the pistons 58 being effected bythe springs 18.

As the pistons 58 so reciprocate they tend to build up pressure in their cylinders 65, these cylinders being lled with oil. As long as the valve stem 89 remains retracted so as to expose the oil ports 85. the oil from the cylinder of an inwardly moving piston 58 is free to flow through its passage 85 and port 85 into the bore 45, 59 of the shaft |I. From the bore the oil is free to travel out through the opposite oil port 88 and its passage 86 into the opposite cylinder 85, the piston 58 of which is traveling outwardly at the same rate of speed as the inwardly which at this time are traversing the groove 55 in the working face 59 of the enclosing cylindrical shell 55. Thus, the oil forced by the inwardly moving pistons into the working chamber ofthe enclosing cylindrical shell 55, through the passage 9|, is free to escape through the groove.

- 5 55, ports 5| of the shoes 'I5 and bores 12, 1| of the pistons 58 into the cylinders 55 of those pistons 58 which are moving outwardly at this time. It will therefore be seen that as lons as the valve stem 59 remains retracted` or open there is free interchange of thev oil from the cylinders 55 of the inwardly moving pistons 55 to the cylinders 55 of the outwardly moving pistons 58, either directly across the ports of thesel cylinders. or indirectly through the bore I9, passage 9|, working chamber of the `enclosing cylindrical shell 55, groove 54 and ports 8| and bores ll of the outwardlyy moving pistons. Since no resistance. other than the slight resistance offered by friction, is made to thefree reciprocation of the pistons 55, the cylindrical shell 55 is not rotated on th hubs 55 and 55, and hence the driven sprocket 55 xed to this cylindrical shell 55 likewise remains stationary. This sprocket is xediconcentric with the shaft. so that it does not oscillate when the cylindrical shell 55 is turned.

To' establish a drive, the operator shifts the valve'rod 89 axially inward so as to close oil', to the desired degree, the ports 55. It will be noted lthat on traversing the ungrooved portion of the face 58 of the enclosing cylindrical shell 55, the.

pistons 58 are moved vinwardly by the eccentricity of this face, and that on traversing the groove 84 the pistons. 58 are moved outwardly by their springs 14. Therefore, when the valve stem 59 is moved to completely seal the ports 55 the pistons are locked against inward movement and hence lock the enclosing cylindrical shell 55 to the cylinder block to rotate therewith. Thus, the cylinders 55 of those pistons 55 traversing the ungrooved half of the face 59, and which pistons v would normally be moved inwardly by the eccentricity of the enclosing cylindrical shell 55, have their inner ports 88 sealed by the valve stem 88 and have their outer ports 8| sealed by the ungrooved half of the working-face 59. Since no I fluid can escape from the cylinders 55 of those pistons 58 traversing the ungrooved half of the working face 59 and since the eccentricity of this ungrooved half of this working face tends to drive these pistons inwardly, it will be seen that the shoes 'I5 of these pistons become wedged against this ungrooved half of the working face 59 to provide a positive interlock between the cylinder block 52 and the enclosing cylindrical shell 55. Consequently a positive drive is established between the driving pinion 6 and the driven pinion 54.

Any. desired slippage of the clutch can be provided by adjusting the valvestem 89 to restrict the ports 58 to a corresponding degree.' In such partially closed condition the pistons 58 are reciprocated and the fluid movement is the same as when the clutcl is fully opened except that the movement of the pistons 68 is retarded so as to provide a yielding wedging action between the cylinder block 52 and the enclosing cylindrical shell 55, the degreeof this yielding being, however, under positive control. v

Thus, those cylinders 56 whose shoes 15 are traversing the groove 85 of the working face 59 are open to the interior of the enclosing cylindrical shell 55, the oil in this enclosing cylindrical shell 55 being free to ow through the groove 84, ports 8| and bores 12, 1| into these cylinders 55 as illustrated by the upper'ieft hand cylinders 65 in Fig. 2. The springs 14 are therefore free to drive the pistons 68 outwardly while this grooved half oi' .the face 59 is being traversed, the eccentricity ly increased amount of the oil escaping from of this grooved half of the face Bl permitting such outward movement of the pistons. When the port II of each shoe reaches the end of the groove 8l itis closed by the face 5l of the enclosing cylindrical shell and at the same time the eccentricity of this face 59 starts to drive `this shoe 15 and its piston Il inwardly. Therefore, while the shoes 15 and pistons C8 are traversing the ungroovedhalf of the face 59 and are being driven inwardly "thereby, theiluid in their cylinders -86 can only escape through the .ports I8. As these ports 88 have been partly restricted by the valve stem ll the rate of inward movement of these pistons I8 is determined lby the rate of escape of the iluid through the ports ll, this, in turn. controlling the rate of travel of the shoes 1B along the ungrooved half of the face El and hence the degree of slippage between the cylinder block 52 and the enclosing cylindrical shell l5.

When the ports I8 are so partly restricted a part of the iiuid escaping from these ports can flow directly through the opposite ports B8 and into the cylinders t8 of those pistons I8 which are traversing the grooved half of the working face Il and hence are being moved outwardly by .their springs 1I. However, these opposite ports Il are also restricted and hence a correspondiitilgle ports 88 of the inwardly moving pistons escape through the bore 48, and passage 8l tothe interior of the enclosing cylinder 55 where it is free to enter the cylinders lt of the outwardly moving pistons through the groove Il, ports BI and bores 12, 1 I.

It will be observed that on reverse torque, .that is, when the enclosing cylindrical shell Bl and its sprocket 84 become the driver as when going down a steep grade. the clutch becomes free wheeling or opens to permit coasting regardless of the position of the valve rod 80. Thus, under this reverse torque condition the grooved half of the face I9 becomes that part which drives the pistons 5I inwardly and the ungrooved half of this face will Y 8 track along the face 59 on reverse torque. These check valves 93 are only operative under conditions of reverse torque and hence the wear is slight.

Since .the clutch as shown is .open on reverse torque. it will be seen that it could be used as a socalled free-wheeling clutch, independent of any other control. Thus. the inner ends of thecylinders I6 could be blind or permanently sealed. and the clutch would function to drive in one direction but be open when conditions of reverse torque are encountered.

It will be noted, that' in action, the centrifugal force tends to build uppressure in the outer .part of the clutch thereby to insure the full feed of fluid to the cylinders BI through the groove Il. A further feature of .the invention resides in the a mounting of the cylinders with their axes form- 59 becomes that part which releases the pistons. l

Since the cylinders 66 of the pistons 68 so being driven inwardly by the grooved half of the face Il are open to the interior of the enclosing cylinder 5B through their bores 1I, 12, ports 8| and the groove ll, it is apparent that the shoes of these pistons cannot wedgel against the grooved half of the face I! to establish a drive on reverse torque. On Vthe other hand, if the valve stem 89 were adjusted at this time to fully seal the ports Il, when each shoe 15 reached the end of the groove 84 both ends of its cylinder 80 would be sealed and since the springs 14 would probably not be powerful enough to establish a vacuum in the cylinders ll while traversing the ungrooved half of .the face $9, means are provided for admitting fluid to the cylinders $6 at this time.

While various means could be employed for this purpose, the simple check valve Il for each cylinder 86 is satisfactory. It will be noted that each check valve 83 opens toward its cylinder 68 and hence insures that thepressure in lthe enclosing cylindrical shell B5 never substantially exceeds the pressure in each cylinder 88. Thus, on reverse torque, when each shoe 15 encounters the ungrooved half of the face 5l the lowered -pressure in its cylinder Il, induced by its spring 1I, opens its check valve I3 so that fluid is free to now from the enclosing cylinder IB, past .the check valve 93 and through the passage 89, port Il and bore 1I. 12 into the corresponding cylinder The shoes 18 are thereby rendered free to ing a square surrounding the axis of the shaft I I. This provides, in effect, a lever arm supporting each plunger or piston 88 which not only brings the pistons closer into axial alinement with -the opposing force of .the enclosing cylinder Il but also greatly reduces side thrust of each plunger or piston il against its cylinder walls. The plungers can accordingly be made smaller and the simple Y ball-and-socket joint 'between each .plunger 68 and its shoes 151s feasible.' Further, as the liquid in the clutch expands or contracts under temperature change, this liquid is free to ilow back and forth between the enclosing cylinder Il and the transmission case l through .the bore 4I and passage 8| in the shaft II. This further renders the gear or transmission case l a large reservoir for the clutch .fluid since the level in the transmission case would have to drop below the bore II- of the shalt II before the clutch would lose its oil; There is also a degree of interchange between the oil in the clutch and the oil in the Atransmission case so that the surfaces of both are available to cool the oil. the top of the cylindrical shell l5. as in failing to bleed the plug IIl0, this body of air would be driven into the cylinders 88 by the centrifugal force of the liquid. and this air would bubble along .the bore I I to the transmission casing B and be vented. A partially filled condition of the clutch is therefore self-remedying within a comparatively short length of time.

The present invention therefore provides a very simple. compact and strong hydraulic clutch which is unidirectional in its action and is automatically opened in the opposite direction. The,

clutch is also free from wearing diificulties, particularly if a wedge-shaped crevice is left at the noseof each shoe to providev a molecular congestion of the liquid therein. The clutch also has the numerous speciilcadvantageous features heretofore discussed. A

1. A clutch of the character described for releasably coupling-a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts, a. cylindrical shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but in eccentric relation to the axis of said cylinder block and forming a chamber containing aliquid surrounding said cylinder block, s aid cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with-its axis in a plane at right angles to the axis of said cylinder block, a piston in each of said cylinders and projecting outwardly therefroma shoe secured to the outer end of each of said pis- Further, if air should get caught in I tons and having a face engaging the inner cylindrical face of said cylindrical shell to reciprocate said pistons in response to the rotation oi' said cylindrical shell relative to said cylinder block, each of said pistons being provided with a bore communicating with the corresponding cylinder and each 'of said shoes being provided with an internal passage registering with the bore oi the corresponding piston, and means for admitting liquid from said chamber through each of said passages and the corresponding bore to the corresponding cylinder when the piston is moving outwardly in following the corresponding haii' oi' I said inner cylindrical face and restraining the reverse movement of said uid through said passage and bore when said piston is moving linwardly in following the other half of said inner cylindrical face.

2. A clutch of the character described for releasably coupling a driving part and a driven part. comprising a cylinder block secured to rotate with one of said parts, a cylindrical shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block, said cylinder block being formed to provide a plurality`oi cylinders open at their outer ends and each arranged with its axis in a plane 'at right angles to the axis of said cylinder block. a piston in each of said cylinders and projecting outwardly therefrom. a shoe secured to the outer end oi each of said pistons and having a face engaging the inner cylindrical face of said cylindrical shell to reciprocate said pistons in response to the rotation of said cylindrical shell relative to said cylinder block, each of said pistons being provided with a bore communicating with the corresponding cylinder and each of said shoes being provided with an internal passage registering withl the bore of the corresponding piston, and means for admitting liquid from said chamber through each of said passages and the corresponding bore to the corresponding cylinder when the piston is moving outwardly in following the corresponding half of said inner cylindrical face and restraining the reverse movement of said liquid through said passage and bore when said piston is movinginwardly in following the otherl half of said inner cylindrical face, comprising a circumferential groove providedin said corresponding half oi said inner cylindrical face and arranged to register with a port provided by the said passage in each of said shoes.

3. A clutch of the character described for releasably coupling a driving part and a driven part,

comprising a cylinder block secured to rotate with one of said parts, a cylindrical shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block, said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane at right angles to the axis of said cylinder block, a piston in each of said cylinders and projecting outwardly therefrom, a shoe secured to the outer end of each of said pistons and having a face engaging the inner cylindrical face of said cylindrical shell to reciprocate said pistons in response to the rotation of said cylindrical shell `relative to said cylinder block, each of said pistons being provided with face. comprising av circumferential groove pro.- vided in said corresponding half of said inner cylindrical face and arranged to register with a port provided by the said passage in each of said shoes, means at the inner endof each cylinder and permitting the escape oi liquid from said cylinders when the pistons are so moving inwardly in following said other half oi said inner cylindrical face, and means adjustably controlling said escape of liquid to permita corresponding slippage ofthe clutch.`

4. A clutch oi the character described for releasably coupling a driving part anda driven part, comprising a cylinder. block secured to rotate with one of said parts, a cylindrical shell enclosing said cylinder block and secured to rotate with the other ci said parts with its axis parallel with but in eccentric relation to the axis of said cylinder block and forming a chamber containing agliquid 4surrounding said cylinder block. said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane at right angles to the axis of said cylinder block, a piston in each oi said cylinders and projecting outwardly therefrom, a shoe having a ball-andsocket connection with the outer end. of eachl piston toy provide. continuously engaging faces therebetween, each oi said shoes also having a face engaging the inner cylindrical yiace of -sald enclosing cylinder to reciprocate said pistons in response tothe rotation of said cylinder block relative .to said cylindrical shell, each of said pistons being provided with a bore communicating with the corresponding cylinder and each oi said shoesbeing provided with a passage com` municating through the facesv o! said ball-andsocket joint with the bore of the corresponding piston, and means for admittingliquid from said chamber through each oi said passages tothe corresponding cylinder when the piston therein is moving outwardly in following the corresponding half of said inner cylindrical face and restraining a reverse flow ci said admitted liquid when each piston is moving inwardly in following the other half of said inner cylindrical face.

containing a liquid surrounding said .cylinderv bloclnsaid cylinder block being formed to provide a plurality oi cylinders open at their outer ends and each arranged with its axis in a plane at right angles to the axis of said cylinder block, a'

piston in each oi said cylinders and projecting outwardly therefrom. a shoe secured to the outer end of each of said pistons and having a face engaging the inner cylindrical face oi said cylin- In drical shell to reciprocate said pistons in response 'to the rotation of said cylindrical shell relative to said cylinder block, each of said pistons being provided with a bore communicating with the corresponding cylinder and each of said shoes being provided with an internal passage registering with the bore of the corresponding piston, and means for admitting liquid from said chamber through each of said passages and the corresponding bore to the corresponding cylinder when the piston is moving outwardly in `following the corresponding half of said inner cylindrical face and restraining the reverse movement of said fluid through said passage and bore when said piston is moving inwardly in following the other half oi' said inner cylindrical face and including a check valve opening from said chamber toward the corresponding bore.

6. A clutch of the character described for releasably coupling a driving part and a driven part. comprising a cylinder block secured to rotate with one of said parts, a cylindrical shell 4enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding .said cylinder block, said cylinder Iblock being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane at right angles to the axis of said cylinder block, a piston in each of said cylinders and projecting outwardly therefrom, a shoe secured to the outer. end of each of said pistons and having a face engaging the inner cylindrical face of said cylindrical shell to reciprocate said pistons in response to the rotation of said cylindrical shell relative to said cylinder block, each of said pistons being provided with a bore communicating with the corresponding cylinder and each of said shoes the inner cylindrical face of said cylindrical shell" to reciprocate said pistons in response to the rotation of said cylinder block relative to said cylindrical shell, and means for admitting liquid directly from said chamber to each cylinder when the piston therein is moving outwardly in following the corresponding half of said inner cylinydrical face and restraining a reverse ilow of said admitted liquid when each piston is moving inwardly in following the other half of said inner cylindrical face.

8'. A clutch of the character described for ren leasably coupling a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts, a cylindrical shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but in `eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block. said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane generally at right angles to the axis oi' said cylinder block'and said axes of said cylinders being at an angle to each other to form a regular polygon concentric with the axis of said cylinder block, a piston in each being provided with a passage communicating with Ithe bore of the corresponding piston, and

means for admitting liquid from sa'id chamber 'through each of said passages and the corresponding bore. to the corresponding cylinder when the piston is moving outwardly in following the corresponding half of said inner cylindrical face cylinder and projecting outwardly therefrom, and provided with a rounding face at its outer'end. a shoe having a rounding face movably contacting the said rounding face at the outer end of each piston and having a face fitting the inner cylindrical face of said cylindrical shell to reciprocate said pistons in response to the rotation of said cylindrical shell relative to said cylinder block,

each of said pistons being-provided witha bore cylindrical face and restraining a reverse flow of and restraining the reverse movement of said .l

iluid through said passage and bore when said 4piston is moving inwardly in following Ithe other half of said inner cylindrical face. each of said shoes being provided ony its opposite sides with ilanges conforming to the inner cylindrical face of said cylindrical'shell and the opposite side walls of said shell being formed to provide circular tracks engaging said flanges to retain 4said i shoes against the inner cylindrical face of said shell.

7. A clutch of the character described for releasably coupling a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts and being square in cross section in a plane at right angles to its axis, a cylindrical shell enclosing said cylinder block and secured to rotate with the other of said -parts with its axis parallel with but in eccentric said admitted liquid through each bore when the corresponding piston is moving inwardly in following the other half of said inner cylindrical face.

9. A clutch of the character described for releasably coupling a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts, a cylindrical shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis g parallel with but in eccentric relation to the axis of said cylinder block and forminga chamber containing a. liquid surrounding said cylinder block, said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane ,generally at right angles to the axis of said cyli3 e municating with its cylinder, and each of said shoes being provided with an internal passage registering with the bore of the corresponding piston, and means for admitting liquid from said chamber through each of said 'passages and the correspondingbore when the piston is moving outwardly in following the corresponding half of said irner cylindrical face and restraining theA reverse movement of said uid through said passage and bore when said piston is moving inwardly in following the other half of said inner cylindrical face.

l0. A clutch of the character described for releasably coupling a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts, a shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but radially inwardly facing working face in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block, said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged with its axis in a plane generally at right angles to the axis of said cylinder block, a piston in each of said cylinders and eprojecting outwardly therefrom, a shoe movably secured to the outer end of each of said pistons and having a face engaging said working face of said shell to reciprocate said pistons in response to the rotation of said shell relative to said cylinder block, each of said pistons being provided with a, bore communicating with the corresponding cylinderand each of said shoes being provided with an internal passage registering with the bore of the corresponding piston` and means for admitting liquid from said chamber through each of said passages and the corresponding bore to the corresponding cylinder when the piston is moving outwardly in following the corresponding part of said working when each piston is moved inwardly in following the corresponding part of said working face.`

12. A clutch of the character described for releasably coupling a driving part and a driven part, comprising a cylinder block secured to rotate with one of said parts, a shell enclosing said cylinder block and secured to rotate with the other of said parts with' its axis parallel with but having a radially inwardly facing working face in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block, said cylinder block being formed to provide a plurality of cylinders open at their outer ends and each arranged in a plane generally at right angles to the axis of said cylinder block, a piston in each of said cylinders and projecting outwardly therefrom, a shoe movably secured to the outer end of each' of said pistons and having a face engaging said working face of said shell to reciprocate said pistons in response to the rotation of said shell [relative to ing with the bore of the corresponding piston,

face and restraining the reverse movement of liquid through said -passage and bore when said piston is moving inwardly in following the corresponding part of said working face, comprising a. circumferential groove provided in said shell along said rst correspondingpart of said working vface and arranged to register with a post provided by the said passage in each of said shoes.

ll A clutchv of the character described, for releasably coupling a driving part and a driven part. comprising a cylinder block secured to rotate with one of said parts, a shell enclosing said cylinder block and secured to rotate with the other of said parts with its axis parallel with but having a radially inwardly facing working face in eccentric relation to the axis of said cylinder block and forming a chamber containing a liquid surrounding said cylinder block, said lcylinder block being formed to provide a plurality ot cylinders open at their outer ends and each arranged with its axis in a plane generally at right angles to the axis of said cylinder block, a piston in each of said cylinders and projecting outwardly therefrom, a shoe having a rounding extension and socket connection with the outer end of each piston to provide continuously engaging faces therebetween, each of said shoes also having a face engaging said working facel of said shell to reciprocate said pistons in response to the rotation of said shell relative to said cylinder block, each and means for admitting liquid from said chamber through each of said passages and the corresponding bore to the corresponding cylinder when the piston is moving outwardly in following th'e corresponding part of said working face and restraining the reverse movement of said liquid through said passage and bore when said piston is moving inwardly in following the corresponding part of said working face,l each of said shoes being provided on its opposite sides with flanges generally conforming to the face of said shoe engaging said working face of said sh'ell and the opposite side walls of said shell being formed to provide endless tracks receiving said flanges to retain said shoes in operative relation to said f working face of said shell.

` ALBERT r'. nIcKMAN.;

REFERENCES VCITED The following references are of record in the file of this patent:

- UNITED STATES PATENTS' 

